The present invention generally relates to glare, and the subjective nature of glare perception. More specifically, the present invention relates to apparatuses, methods, and systems for quantifying what is primarily a subjective experience (i.e., glare perception), and in a manner that is useful for lighting design.
It is generally understood that any source that provides light may produce glare. It is also generally understood that while the process of seeing is fairly objective and affected by a number of known factors, the perceiving of glare remains a fairly subjective experience affected by some number of both known and unknown factors. While significant efforts have been spent in the lighting industry to measure glare (see, e.g., discussion of various glare models in Clear, RD. Discomfort glare: What do we actually know? Lighting Research & Technology 2012; 0: 1-18, incorporated by reference herein), and significant efforts have been spent designing lighting systems to minimize glare (see, for example, U.S. Pat. Nos. 5,211,473 and 7,988,326, and published patent application US2013/0250556 A1 (U.S. patent application Ser. No. 13/897,979) the lattermost incorporated by reference herein), there has been little agreement to date as to when glare poses an actual problem and which model for characterizing glare is appropriate for which situations—as it is generally understood that no single model for characterizing glare is appropriate for all situations (see again the aforementioned paper). So while it is understood that “glare science”—as it will be called herein—is ever advancing, practical applications of glare science have yet to be realized. That being said, a number of industries would benefit from an enhanced understanding of the human experience as it relates to glare; in particular, the lighting design industry.
A number of lighting design tools are well known in the industry: there exist tools to characterize a light source—or luminaire in terms of candela (see, e.g., any of the model AMS goniophotometers commercially available from Instrument Systems GmbH, Berlin, Germany); there exist tools to calculate vertical and horizontal footcandles based on the aforementioned candela data so to validate generated (i.e., virtual) lighting designs (see, e.g., AGi32 software commercially available from Lighting Analysts, Littleton, Colo., USA); there even exist tools to create photorealistic renderings of lighting designs overlaid on photographs of unlit sites (see, e.g., U.S. Pat. No. 8,928,662 the entirety of which is incorporated by reference herein), and tools to predict light levels in a virtual space prior to its construction (see, e.g., the Radiance Synthetic Imaging System available for download at http://radsite.lbl.gov/radiance/HOME.html homepage (website accessed 2015 May 1)). Each of the aforementioned tools serves a purpose and plays a role in achieving an ultimate goal: adequately lighting a target area (i.e., application area) as viewed from one or more vantage points to one or more specifications for one or more situations.
Since it has been stated that any source that produces light has the potential to produce glare, and any lighting design includes at least one light source, and a viewer at a number of vantage points could perceive glare from said source, it is readily apparent that the art of lighting design would benefit from somehow integrating glare analysis into existing lighting design tools. Yet while glare science has demonstrated the need for considering glare in lighting design, there exist only limited tools with which to do so. For example, some manufacturers of the aforementioned lighting design software do permit calculation of glare; to date, a Glare Rating (GR) as defined by the International Commission on Illumination (see, e.g., CIE 112-1994) or even a Unified Glare Rating (UGR) as defined by CIE 117-1995. However, as has been stated, no one glare model (GR, UGR, or otherwise) is appropriate for all situations, and no one glare model adequately addresses both discomfort and disability glare under most situations. Further, state-of-the-art glare calculation in lighting design software is limited to reporting numbers on a grid; adequate for demonstrating adherence to any governing codes or standards, but providing very little context for the owner or user of the yet-to-be-manufactured lighting system. A user or owner may benefit from a visualization of glare—seeing which light sources are potential glare sources under different conditions (e.g., varying adaptation levels, different lines of sight). Further, glare calculations using existing lighting design tools do not address lighting systems already installed. If a user is experiencing discomfort in his/her office space, for example, there are not tools available to bring to the actual space, quantify what is primarily a subjective experience by the user, and identify ways to correct the situation (or avoid it in future lighting projects). As such, the art of lighting design is limited in the ways in which and to what degree glare science may be incorporated and thus, there is room for improvement in the art.